The present technique relates generally to the measurement of motion in medical imaging. More specifically, the present technique relates to the use of sensors and/or image data to measure the three-dimensional motion of an organ.
In the medical field, it is often desirable to generate images of the internal organs or structure of a patient for diagnosis or examination. For example, magnetic resonance imaging (MRI) and computed tomography (CT) are two well known examples of imaging modalities used to generate images of the internal organs or structures of a patient. The reconstructed images, however, may be flawed or contain artifacts due to the motion of internal organs, such as the heart, lungs, diaphragm, stomach, and so forth. In particular, if the imaged region has undergone motion during the imaging process, various motion-related artifacts or discontinuities may be present in the reconstructed image.
For example, images acquired of one or more organs in the torso of a patient, such as the heart, lungs, stomach, and so forth, may have motion-related artifacts associated with cardiac and/or respiratory activity. One problem that may arise in attempting to estimate the motion of an imaged organ is that the various techniques employed may not provide sufficient motion information in all of the dimensions of interest.
For example, sensors that measure mechanical motion or some characteristic of motion may be situated on the patient. Such sensors may measure a variety of parameters, such as displacement, pressure, velocity, acceleration, and so forth, which may be processed to characterize the internal motion of one or more organs. However the motion characterization derived from such an external sensors or sensors is typically one-dimensional, i.e., motion is only described along a single axis spanning the sensor and the organ. Due to the shape of the human body, however, it is typically difficult to situate three mechanical sensors sufficiently near to an organ of interest such that the sensors are orthogonal to one another. The three-dimensional motion of the organ, therefore, cannot be easily described using mechanical sensors.
Similarly, image data, such as pre-acquisition data in the form of a Navigator Echo generated by an MRI system, may be used to measure organ motion. Such techniques, however, require anatomical landmarks that can be easily distinguished and used to gauge motion. Such landmarks are generally not available along all three-dimensions for most organs of interest. As a result, pre-acquisition image techniques may also be essentially one-dimensional in characterizing motion. At the very least, such techniques are not generally useful for characterizing the motion of an organ in three-dimensions. The absence of reliable data describing the three-dimensional motion of an imaged organ may impair efforts to reduce or eliminate motion-related artifacts in the image data. It is, therefore, desirable to develop a technique for reliably estimating the motion of an imaged organ in three-dimensions with good temporal resolution.